This invention pertains to reinforcement blanket useful for making fiber-reinforced articles.
As one of its more specific aspects, this invention pertains to a reinforcement blanket which comprises various combinations of layers of random preformable or standard continuous strand mat and layers of unidirectional or multidirectional reinforcement material placed in a predetermined specified sequence and sewn together for ease in handling as a single blanket unit. In one embodiment the reinforcement blanket is preformed to a desired shape for use in molding various structural applications such as large, complex automotive shapes.
The production of glass fiber-reinforced materials into useful shapes is well-known. Normally, a glass reinforced fibrous mat is preformed and then placed in a mold for molding into a fiber-reinforced article. Typically, glass fiber-reinforcement mats are used in situations where a desired strength is necessary, such as in automobile bumpers. For example, layers of the continuous strand mat and layers of unidirectional or multidirectional reinforcement material are fabricated separately. These layers are individually placed in a set of preform screens which generally consist of an upper screen and a lower screen. The upper and lower screens are moved together in order to conform the layers to the shape of the preform screens. The layers are thus shaped into what is known as a preform. The preform is then placed in a mold and injected with a suitable resinous material to make the fiber-reinforced article. However, problems occur in the production of the glass fiber-reinforced articles when layers of the unidirectional or multidirectional reinforcement material are layered adjacent each other when making the preform. Often the adjacent layers of the unidirectional or multidirectional material move relative to one another and delamination sometimes occurs during the preforming process and subsequent handling of the preform.
Further, the production of the fiber-reinforced articles is a time-consuming process since the manufacture of the fiber-reinforced articles includes at least two time-consuming steps: first, the each individual layer of continuous strand mat and unidirectional or multidirectional reinforcement material must be individually placed in the preform screen in order to form a preform; and second, the preform is thereafter placed in a mold and impregnated with a matrix resin and cured to form the final article.
It would be beneficial if various combinations of different fibrous reinforcement materials could easily be fabricated into reinforcement blankets which could then be easily shaped into the final preform for molding into a product or articles.
Further, it would be beneficial if glass fiber-reinforced articles could be made without compromising the integrity of the preform due to delamination of the fiber-reinforcement mat during the preform shaping process and subsequent handling of the preform.